Sewing system with thread draw tension adjusting capability and a method of adjusting the thread draw tension

ABSTRACT

The combination of a bobbin assembly and a support for the bobbin assembly. The bobbin assembly has a core around which a supply of thread can be wrapped. The core has a rotational axis. The bobbin assembly further has a first flange with first and second oppositely facing surfaces, with the first surface bounding a storage space for thread wrapped around the core. The support allows the bobbin assembly to rotate around the rotational axis. The support has a third surface facing the second surface with the bobbin assembly operatively connected to the support. The bobbin assembly and support are magnetically attracted to each other with a force of a first magnitude with the bobbin assembly and support in a first state. The force resists rotation of the bobbin assembly around the rotational axis. At least one of the bobbin assembly and support is reconfigurable to cause the bobbin assembly and support to be one of a) not magnetically attracted to each other and b) magnetically attracted to each other with a force of a second magnitude, that is different than the first magnitude, with the bobbin assembly and a support in a second state.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to sewing systems utilizing a bobbinassembly, upon which a supply of thread is wrapped, and a support,relative to which the bobbin is rotated as the thread is draw off of thebobbin assembly. More particularly, the invention is directed to amethod and structure for selectively, variably controlling tension onthe thread as the thread is drawn off of the bobbin assembly.

[0003] 2. Background Art

[0004] In one conventional sewing system, a supply of thread is woundaround a bobbin. The bobbin is mounted on a post within a case forrotation relative to the post axis. Thread is directed from the bobbinthrough an opening in the peripheral wall of the case to be engaged by arotary loop taker. During system operation, the rotary loop taker exertsa force on the thread, i.e. a draw tension, that causes the bobbin torotate in a manner that thread thereon is paid out.

[0005] An important factor in producing a consistent quality stitch isthe ability to maintain a desired thread draw tension. Ideally, theforce/thread draw tension required to extract the thread is maintainedwith a full thread supply up to the point that the thread supply isfully exhausted.

[0006] Various mechanisms have been devised to controllably adjust thethread draw tension. One such system, commonly used, employs a leaf-typespring element with a friction surface which confronts the outer wall ofthe case in a region at which the thread departs from the case opening .A captive frictional force, between the leaf-type spring element andcase, can be varied by selectively setting an adjusting screw.

[0007] Another system for controlling thread draw tension is disclosedin U.S. Pat. No. 6,152,057. In this system, thread departing from thecase opening is wrapped spirally around an elongate member to produce acontrolled resistance to thread withdrawal. The degree of resistance canbe set by strategically selecting a) the number of wraps of the threadaround the elongate member, b) the frictional characteristics of thematerial on the exposed surface of the elongate member about which thethread is wrapped, etc.

[0008] It is also known to produce a force resisting rotation of abobbin relative to a supporting case. This resisting force may bedeveloped to prevent backlash and/or to control thread draw tension. Anexample of one such system is shown in U.S. patent application Ser. No.09/794,702. In this system, frictional resistance is developed between aflange on the bobbin and an adjacent case surface. More specifically,flexible elements act between these surfaces to produce forces resistingrotation of the bobbin.

[0009] In U.S. patent application Ser. No. 09/825,417, magneticattractive or repulsive forces are generated between the bobbin andcase. These rotation resisting forces are predetermined and remainconstant as the system is operated.

[0010] The sewing industry continues to seek out system designs thatwill permit a more constant thread draw tension to be maintained,regardless of the amount of thread on the bobbin. Those systems,described above, that require tension adjustment, may be labor intensiveand may require skilled personnel to effect the necessary adjustments.In large systems, multiple adjustments must be made at differentlocations. Each time such an adjustment is made, trial and error may berequired to assure that the appropriate thread draw tension has beenset. Thus, these systems may become relatively expensive to operate.

[0011] Those systems that do not have any thread draw tension adjustingcapability are limited in that the resistance to rotation is constant,as a result of which the thread draw tension will vary depending uponthe volume of thread upon the bobbin. With such systems, it is commonfor bobbins to be removed from operation with a significant amount ofthread thereon. The thread draw tension increases progressively as thethread supply is exhausted. At some point, the thread draw tensionincreases detrimentally to the point that stitch quality may becompromised. This point may be reached with a significant amount ofthread remaining on the bobbin. Thus, significant thread waste mayresult, particularly in high volume operations.

SUMMARY OF THE INVENTION

[0012] In one form, the invention is directed to the combination of abobbin assembly and a support for the bobbin assembly. The bobbinassembly has a core around which a supply of thread can be wrapped. Thecore has a rotational axis. The bobbin assembly further has a firstflange with first and second oppositely facing surfaces, with the firstsurface bounding a storage space for thread wrapped around the core. Thesupport allows the bobbin assembly to rotate around the rotational axis.The support has a third surface facing the second surface with thebobbin assembly operatively connected to the support. The bobbinassembly and support are magnetically attracted to each other with aforce of a first magnitude with the bobbin assembly and support in afirst state. The force resists rotation of the bobbin assembly aroundthe rotational axis. At least one of the bobbin assembly and support isreconfigurable to cause the bobbin assembly and support to be one of a)not magnetically attracted to each other and b) magnetically attractedto each other with a force of a second magnitude, that is different thanthe first magnitude, with the bobbin assembly and support in a secondstate.

[0013] In one form, there is a magnetic assembly on one of the bobbinassembly and support that is attracted to a metallic portion on theother of the bobbin assembly and support. The bobbin assembly andsupport may be changed from the first state into the second state byseparating a part of the magnetic assembly from the one of the bobbinassembly and support.

[0014] In one form, there is a metallic assembly on one of the bobbinassembly and support that is attracted to a magnetic portion on theother of the bobbin assembly and support. The bobbin assembly andsupport may be changed from the first state into the second state byseparating a part of the metallic assembly from the one of the bobbinassembly and support.

[0015] In one form, the magnetic assembly has a first magnetic element.With the bobbin assembly and support in the second state, the firstmagnetic element is separated from the one of the bobbin assembly andsupport.

[0016] In one form, the magnetic assembly has first and second magneticelements, and with the bobbin assembly and support in the second state,the first magnetic element is separated from the one of the bobbinassembly and support and the second magnetic element remains on the oneof the bobbin assembly and support.

[0017] The first magnetic element may be maintained on the one of thebobbin assembly and support by being magnetically attracted to the oneof the bobbin assembly and support.

[0018] The first magnetic element may be maintained on the one of thebobbin assembly and support by a releasable adhesive.

[0019] The first magnetic element may be otherwise bonded to thecarrier.

[0020] The first magnetic element may be releasably threadably attachedto one of the bobbin assembly and support.

[0021] In one form, the magnetic assembly is maintained on the one ofthe bobbin assembly and support by cooperating releasable connectingparts on the magnetic assembly and the one of the bobbin assembly andsupport.

[0022] In one form, the magnetic assembly has a first magnetic elementwhich is separable from the one of the bobbin assembly and support bytearing a portion of the magnetic assembly to thereby change the bobbinassembly and support from the first state into the second state.

[0023] In one form, the magnetic assembly is provided on the secondflange with the metallic portion at the third surface.

[0024] In one form, the support has a post which guides rotation of thebobbin assembly around the rotational axis and the magnetic assembly ison the post.

[0025] In one form, the magnetic assembly has first and second separatemagnetic elements and a carrier for the first and second magneticelements.

[0026] The carrier may have a weakened portion that can be torn toseparate the first magnetic element from the one of the bobbin assemblyand support to thereby place the bobbin assembly and support in thesecond state.

[0027] In one form, the carrier defines a first receptacle for the firstmagnetic element and a second receptacle for the second magneticelement.

[0028] The carrier may be adhesively bonded to the one of the bobbinassembly and support.

[0029] The magnetic assembly may be frictionally maintained on the oneof the bobbin assembly and support.

[0030] The combination may further include a rotary loop taker fordrawing thread on the bobbin assembly from the bobbin assembly.

[0031] The invention is further directed to the combination of a bobbinassembly and a support. The bobbin assembly has a core around which asupply of thread can be wrapped. The core has a rotational axis. Thebobbin assembly is mounted to the support for rotation around therotational axis. The bobbin assembly and support are magneticallyattracted to each other with a force of a first magnitude with thebobbin assembly and support in a first state . The force resistsrotation of the bobbin assembly around the rotational axis. At least oneof the bobbin assembly and support is reconfigurable to cause the bobbinassembly and support to be one of a) not magnetically attracted to eachother and b) magnetically attracted to each other with a force of asecond magnitude, that is different than the first magnitude, with thebobbin assembly and support in a second state.

[0032] The invention is further directed to a method of controlling drawtension of thread pulled from a supply of the thread. The methodincludes the steps of: providing a bobbin assembly having a core aroundwhich a supply of thread can be wrapped and a rotational axis; providinga support for the bobbin assembly to allow the bobbin assembly to rotatearound the rotational axis; producing a magnetic attractive force of afirst magnitude between the bobbin assembly and support with the bobbinassembly and support in a first state to resist rotation of the bobbinassembly around the rotational axis; and selectively changing thesupport and bobbin assembly to a second state wherein one of a) thesupport and bobbin assembly are not attracted to each other and b) amagnetic attractive force of a second magnitude is produced between thebobbin assembly and support.

[0033] The step of producing a magnetic attractive force may involveproviding first and second magnetic elements on one of the bobbinassembly and support that are attracted to a metallic portion on theother of the bobbin assembly and support.

[0034] The step of selectively changing the support and bobbin assemblyto the second state may involve separating the first magnetic elementfrom the one of the bobbin assembly and support and leaving the secondmagnetic element on the one of the bobbin assembly and support.

[0035] The step of producing a magnetic attractive force may involveproviding a first magnetic element on one of the bobbin assembly andsupport that is attracted to a metallic portion on the other of thebobbin assembly and support.

[0036] In one form, the step of selectively changing the bobbin assemblyand support to the second state may involve separating the firstmagnetic element from the one of the bobbin assembly and support.

[0037] The step of providing a first magnetic element may involveproviding a first magnetic element on a carrier and attaching thecarrier to the one of the bobbin assembly and support.

[0038] In one form, the step of selectively changing the bobbin assemblyand support may involve tearing the carrier to allow separation of thefirst magnetic element from the one of the bobbin assembly and support.

[0039] The step of providing a first magnetic element may involvereleasably attaching the first magnetic element to one of the bobbinassembly and support.

[0040] In one form, the step of producing a magnetic attractive forcemay involve providing first and second metallic elements on one of thebobbin assembly and support that are magnetically attracted to the otherof the bobbin assembly and support.

[0041] In one form, the step of selectively changing the bobbin assemblyand support to a second state involves separating the first metallicelement from the one of the bobbin assembly and support.

BRIEF DESCRIPTION OF THE DRAWINGS

[0042]FIG. 1 is an exploded, partially schematic, elevation view of asewing system consisting of a bobbin assembly on a support in captiverelationship between a bobbin basket and bobbin case and associated witha rotary loop taker and with a magnetic assembly, according to thepresent invention, incorporated so as to allow selective thread drawtension adjustment;

[0043]FIG. 2 is a perspective view of the bobbin assembly of FIG. 1 withthe magnetic assembly thereon;

[0044]FIG. 3 is a cross-sectional view of the bobbin assembly takenalong line 3-3 of FIG. 2;

[0045]FIG. 4 is an enlarged, fragmentary, cross-sectional view of theconnection between a magnetic element on the magnetic assembly and aflange on the bobbin assembly, taken along line 4-4 of FIG. 2;

[0046]FIG. 5 is a plan view of the bobbin assembly in FIG. 2 andreconfigured by removing a plurality of the magnetic elements on themagnetic assembly;

[0047]FIG. 6 is an enlarged, plan view of the bobbin assembly in FIG. 1with a modified form of magnetic assembly, according to the presentinvention, thereon;

[0048]FIG. 7 is a view as in FIG. 6 with another modified form ofmagnetic assembly;

[0049]FIG. 8 is a view as in FIG. 6 with another modified form ofmagnetic assembly;

[0050]FIG. 9 is a view as in FIG. 6 with still another modified form ofmagnetic assembly;

[0051]FIG. 10 is a view as in FIG. 6 with yet another modified form ofmagnetic assembly;

[0052]FIG. 11 is a view as in FIG. 4 and showing a modified structurefor attaching a magnetic element to the bobbin assembly flange utilizinga paper carrier;

[0053]FIG. 12 is a view as in FIG. 11 wherein a solid plastic carrier isutilized in place of the paper carrier in FIG. 11;

[0054]FIG. 13 is a view as in FIG. 10 of a still further modified formof magnetic assembly, according to the present invention, and includinga carrier;

[0055]FIG. 14 is a cross-sectional view of the magnetic assembly takenalong line 14-14 in FIG. 13;

[0056]FIG. 15 is a plan view of one of the magnetic elements on themagnetic assembly in FIGS. 13 and 14, separated from the remainder ofthe magnetic assembly, and including a part of the carrier;

[0057]FIG. 16 is a cross-sectional view, corresponding to that in FIG.4, of a modified form of flange and magnetic element according to thepresent invention;

[0058]FIG. 17 is an exploded view of the flange and magnetic element, asin FIG. 16, and including another form of magnetic element which can beselectively substituted for the magnetic element shown in FIG. 15;

[0059]FIG. 18 is a view as in FIG. 16 of a modified form of magneticelement which is flush with an exposed surface of the flange;

[0060]FIG. 19 is a view as in FIG. 18 wherein the flange is made from adifferent material than is shown in FIG. 18;

[0061]FIG. 20 is an exploded view, corresponding to that in FIG. 16,wherein connecting elements are used to releasably maintain the magneticelement attached to the flange;

[0062]FIG. 21 is an exploded, fragmentary, elevation view of a portionof a modified form of flange and magnetic element, wherein the magneticelement is screw-threaded to the flange;

[0063]FIG. 22 is a plan view of the bobbin assembly in FIG. 1 andincluding a metallic assembly in place of the magnetic assembly;

[0064]FIG. 23 is a fragmentary, cross-sectional view of a bobbinassembly flange and support showing a modified form of magnetic assemblycooperating with a metallic insert, according to the present invention;

[0065]FIG. 24 is a fragmentary, cross-sectional view of a magneticassembly cooperating with a metallic portion at the bottom flange of thebobbin assembly in FIG. 1;

[0066]FIG. 25 is a view corresponding to that in FIG. 24 and showing amodified form of magnetic assembly/metallic portion;

[0067]FIGS. 26 and 27 are schematic representations of differentarrangements of cooperating supports and bobbin assemblies incorporatingthe inventive magnetic and metallic assemblies that cooperate withmetallic and magnetic portions;

[0068]FIG. 28 is an enlarged, fragmentary view of a modified form ofmounting post on the support for the bobbin assembly shown in FIG. 1 andincluding a magnetic assembly, according to the present invention;

[0069]FIG. 29 is a cross-sectional view of the post taken along line29-29 of FIG. 28;

[0070]FIG. 30 is an elevation view of a non-walled bobbin assembly withwhich the present invention can be practiced;

[0071]FIG. 31 is a schematic representation of a sewing system having asupport for a bobbin assembly with an elongate element around whichthread is wrapped to control thread draw tension; and

[0072]FIG. 32 is a cross-sectional view of the elongate element takenalong line 32-32 of FIG. 31.

DETAILED DESCRIPTION OF THE DRAWINGS

[0073] In FIG. 1, a sewing machine assembly is shown at 10 and consistsof a bobbin assembly 12 and a two-part support 14 for the bobbinassembly. The support 14 consists of a bobbin basket 16 and acooperating bobbin case 18 which are matable to produce a receptacle at20 for the bobbin assembly 12. The bobbin basket 16 has a cup-shapedbody 22 with a post 24 projecting upwardly from a bottom wall 26. Thepost 24 defines the rotational axis 28 for the bobbin assembly 12, ashereinafter explained. The body 22 of the bobbin basket 16 has aperipheral wall 30 extending continuously around the central axis 28.

[0074] The bobbin case 18 has a top wall 32 from which a sleeve 34depends in concentric relationship with the post 24. A peripheral wall36 depends also from the top wall 32 and extends continuously around theaxis 28. The sleeve 34 has a through bore 38 which continues through thetop wall 32. With the bobbin basket 16 and bobbin case 18 in operativerelationship, the post 24 extends fully through the sleeve 34 so that anotch 40 in the post 24 is exposed above the top wall 32. In thisconfiguration, the peripheral wall 36 on the bobbin case 18 surroundsthe peripheral wall 30 of the bobbin basket 16. A releasable latchassembly at 42 is operable to engage the notch 40 on the post 24 toprevent separation of the operatively connected bobbin basket 16 andbobbin case 18.

[0075] The bobbin assembly 12 consists of a cylindrical core 44 aroundwhich a supply of thread 46 is wrapped. The bobbin assembly 12 furtherhas axially spaced, disk-shaped, upper and lower flanges 48, 50 attachedat the axial ends of the core 44. The core 44 has a through bore 52 toreceive the sleeve 34, around which the bobbin assembly 12 is journalledfor rotation around the axis 28. With the bobbin basket 16 and bobbincase 18 operatively connected, the bobbin assembly 12 is captive betweenthe bottom wall 26 of the bobbin basket 16 and the top wall 32 of thebobbin case 18.

[0076] The flanges 48, 50 have flat, facing surfaces 54, 56,respectively, which cooperatively bound a thread storage space 58. Theflange 48 has a flat surface 60 facing axially oppositely to the surface54 in a confronting relationship with a flat, downwardly facing surface62 on the top wall 32 of the bobbin case 18. The flange 50 has a flatsurface 64 facing oppositely to the surface 56 and confronting a flat,upwardly facing surface 66 on the bottom wall 26 of the bobbin basket16.

[0077] A conventional rotary loop taker 68 is operatively associatedwith the joined bobbin basket 16 and bobbin case 18 and is useable inconventional manner, as well known to those skilled in this art.

[0078] In the embodiment shown in FIG. 1, the surface 62 on the wall 32of the bobbin case 18 has at least a portion that is made from a metalmaterial. To produce a controlled resistance to rotation of the bobbinassembly 12, a magnetic assembly at 70 is provided on the bobbinassembly flange 48. The magnetic assembly 70 and metallic portion of thesurface 62 cooperate to produce a magnetic field, and preferably amagnetic attractive force, between the bobbin assembly 12 and top wall32 of the bobbin case 18 that resists rotation of the bobbin assembly 12relative to the bobbin case 18.

[0079] As seen additionally in FIGS. 2-4, the magnetic assembly 70consists of a plurality of, and in this case four, discrete magneticelements 72, 74, 76, 78, which are attached to the surface 60 on theflange 48. In this embodiment, each of the magnetic elements 72, 74, 76,78 is flat with an arcuate shape. The shape of the magnetic elements 72,74, 76, 78 is shown to be the same, but need not be. Exemplary magneticelement 74 has oppositely facing flat surfaces 80,82. A layer of areleasable adhesive 84 acts between the surface 82 of the magneticelement 74 and the surface 60 of the bobbin assembly flange 48 tomaintain the magnetic element 74 in its operative position, as shown ineach of FIGS. 2-4. Adhesives are commercially available which arecapable of securely holding the magnetic element 74 upon the bobbinassembly 12, so as to follow movement thereof, yet which allow themagnetic element 74 to be peeled away from the bobbin assembly 12 underan axially applied force.

[0080] With the bobbin assembly 12 and support 14 in a first state, asshown in FIGS. 1-4, all four of the magnetic elements 72, 74, 76, 78 areheld firmly in place so that the bobbin assembly 12 and support 14 aremagnetically attracted to each other with a force of a first magnitude.The bobbin assembly 12 is reconfigurable by removing one or more of themagnetic elements 72, 74, 76, 78 to thereby cause the bobbin assembly 12and support 14 to be attracted to each other with a force of a secondmagnitude that is less than the first magnitude. In FIG. 5, the bobbinassembly 12 is shown in a second state wherein two of the magneticelements 74, 78 have been separated from the bobbin assembly 12.

[0081] With a full supply of thread 46 upon the bobbin assembly 12, thedraw tension is lower than it is as the line supply diminishes. This isbecause the rotative force imparted to the bobbin assembly 12 throughthe thread is applied with a moment arm equal to substantially the fullradius of the bobbin assembly 12. As the supply of thread 46 diminishes,the thread is drawn from a location having a considerably shorter momentarm. Accordingly, to maintain a relatively constant draw tension, themagnetic assembly can initially be configured so that the bobbinassembly 12 and support 14 are in the first state, with all of themagnetic elements 72, 74, 76, 78 fixed in place, with a full threadsupply. As the supply of thread 46 is exhausted, the system operator mayremove one or more of the magnetic elements 72, 74, 76, 78, at one timeor at specific intervals, by peeling the same from the flange 48 toplace the bobbin assembly 12 and support 14 in the second state, whereinthe magnetic attractive force between the bobbin assembly 12 and support14 is lessened. This in turn causes a reduction in the resistance torotation of the bobbin assembly 12, and thus a reduction in the drawtension for the thread 46.

[0082] The effect of the magnetic elements 72, 74, 76, 78 on drawtension can be predetermined. The operator can thus be trained as to howto reconfigure, in this case, the bobbin assembly 12, to adjust the drawtension to maintain the same relatively constant. Through a simple step,the operator can access the magnetic elements 72, 74, 76, 78 as byremoving the bobbin assembly 12, and quickly peel one or more of themagnetic elements 72, 74, 76, 78 to make this adjustment. Locatingpatterns 86,88 can be provided on the flange 48 to facilitatereplacement of the removed magnetic elements 74, 78 in FIG. 5 to allowreusing of the bobbin assembly 12.

[0083] The disclosure of arcuate magnetic elements 72, 74, 76, 78 isintended to be exemplary only. Alternative configurations of magneticelements are shown in FIGS. 6-10. Again, these additional embodimentsare intended only to be exemplary, and not inclusive of allconfigurations contemplated by the invention.

[0084] In FIG. 6, five magnetic elements 92, 94, 96, 98, 99 are appliedto the surface 60 of the bobbin assembly 12 in the same manner as themagnetic elements 72, 74, 76, 78 are applied, as previously described.

[0085] In FIG. 7, concentric, ring-shaped magnetic elements 100, 102,are mounted upon the surface 60 of the flange 48. The state of thebobbin assembly 12 and support 14 can be changed by separating one orboth of the magnetic elements 100, 102 from the flange 48.

[0086] In FIG. 8, intermeshed, spiral, magnetic elements 104, 106 areapplied to the surface 60 of the flange 48.

[0087] In FIG. 9, magnetic elements are provided in two different sizeddisk shapes 108, 110. In this configuration, the magnetic elements 108,110 are alternatingly placed in an annular array on the surface 60 ofthe flange 48. The magnetic elements 108, 110 may be selectivelyseparated from the flange 48 to change the state of the bobbin assembly.12 and cooperating support 14.

[0088] In FIG. 10, two different types of magnetic elements 112, 114 areprovided on the surface 60 of the flange 48. The magnetic elements 112,114 are each elongate, with the magnetic elements 112, 114 differingfrom each other in width. The magnetic elements 112, 114 are situatedwith their lengths aligned radially relative to the central axis 28. Themagnetic elements 112, 114, are alternatingly placed around the axis andmay be removed strategically to change the state of the bobbin assembly12 and support 14.

[0089] The use of the adhesive 84 should not be viewed as limiting. Theinvention contemplates myriad ways of releasably attaching magneticelements to the bobbin assembly 12. A description of additionalembodiments will follow. Again, it should be understood that theseadditional embodiments are exemplary in nature only, and not intended tobe limiting or inclusive of all configurations contemplated by theinvention.

[0090] In FIG. 11, the exemplary magnetic element 74 in FIGS. 1-5 isshown connected as by an adhesive layer 116 to a carrier 118. In thiscase, the carrier 118 is a layer of paper or cloth that has weakenedareas 120 coinciding with the boundary of the magnetic element 74, orclosely approximating that shape. The magnetic element 74 may bepermanently bonded to the carrier 118 through the adhesive layer 116. Aseparate adhesive layer 122 bonds the carrier 118 to the surface 60 ofthe flange 48. By drawing the magnetic element 74 away from the flange48, the carrier 118 tears at the weakened areas 120 to allow themagnetic element 74 to be separated from the flange 48. The adhesive inthe layer 122 may be sufficiently tenacious that less than the fullthickness of the carrier will separate within the region within theweakened areas 120. Alternatively, the adhesive in the layer 122 maypermit release of the entire thickness of the carrier 118 within theregion bounded by the weakened areas 120.

[0091] In FIG. 12, the depicted construction differs from that in FIG.11 only by reason of the construction of the carrier 118 from a plasticmaterial. With this construction, the weakened areas 120 are designed toweaken the more rigid carrier 118 to an even greater extent to allow itto be torn. It is also desirable that the adhesive in the layer 122 bereleasable so that excessive resistance is not encountered in separatingthe magnetic element 74, and underlying carrier portion, from the flange48.

[0092] In FIGS. 13-15, a modified form of magnetic assembly is shown at124 and consists of a carrier 126 which encases the ring-shaped magneticelements 100, 102, as shown in FIG. 7 and described hereinabove. Thecarrier 126 consists of spaced layers 128, 130, each having a shapecorresponding generally to the circular shape of the surface 60 on theflange 48. The layers 128, 130 are joined by concentric, annular beadsof adhesive 132, 134, 136, which maintain the layers 128, 130 as aunitary structure and define separate receptacles 138, 140 for themagnetic elements 100, 102, respectively. Annular weakened areas 142,144, 146, 148 define frangible regions which allow the layer 128 to betorn so as to selectively release one or both of the magnetic elements100, 102 to allow separation thereof from the flange 48 to change thestate of the bobbin assembly 12 and the cooperating support 114.

[0093] In FIG. 16, a magnetic element 150, intended to be representativein function of all of the magnetic elements described hereinabove andhereafter, is shown attached to a representative flange 152 by pressfifting the same into an undercut receptacle 154 in the flange 152. Themagnetic element 150 can be press fit into its operative position withinthe receptacle 154 to be selectively frictionally held, and separatedtherefrom, to effect reconfiguration of the flange 152. The magneticelement 150 can take virtually a limitless number of forms. As justexamples, the magnetic element 150 may be in the form of a disc thatextends fully around the bobbin assembly axis, or a small element thatextends only a short distance around the bobbin assembly axis. Thefrictional holding may be accomplished through the body of the element150 itself or through one or more separate anchoring posts 155, orthrough other structure.

[0094] In FIG. 17, a kit is shown in conjunction with the flange 152 andconsisting of the magnetic element 150 and a magnetic element 156, whichcan be interchangeably mounted within the receptacle 154. The magneticelements 150, 156 may have a different magnetic strength to change theattraction between the magnetic element 156 and a cooperating metallicposition/element. The magnetic element 156 is also shown to have anoptional adhesive layer 158 which augments the frictional holding forcebetween the flange 152 and magnetic element 156.

[0095] In FIG. 18, the flange 152 is shown with a magnetic element 160that is flush with the flange surface 162 with the magnetic element 160within the receptacle 154. The corresponding magnetic elements 150, 156in FIGS. 15 and 16 have a thickness that projects to above thecorresponding flange surface 162.

[0096] In FIG. 19, a modification is shown for the flange 152. In FIG.19, the corresponding flange 152′ is made from plastic material whichdefines a receptacle 154′ for the magnetic element 160.

[0097] In FIG. 20, the flange 152 is shown with a receptacle 154 for themagnetic element 150. Cooperating connecting elements 162, 164 areprovided, one each on the flange 152 and magnetic element 150, toreleasably maintain the magnetic element 15 within the receptacle 154.The connecting elements 162, 164 may be conventional hook and loop typefastener. The hook and loop type fastener can be utilized without therequirement of a receptacle. It should be understood that the use of theconnecting elements 162, 164, and other structures in FIGS. 15-18, canbe used with all embodiments disclosed herein.

[0098] A further modified form of magnetic element is shown in FIG. 21at 166. The magnetic element 166 has a male threaded portion 168 toengage within a threaded female bore 170 on a flange 172.

[0099] While the magnetic elements have been described to be on thebobbin assembly 12, as shown in FIG. 22, corresponding elements 72′,74′, 76′, 78′ on a corresponding flange 48′ may constitute a metallicassembly 172, as part of the bobbin assembly 12, to cooperate with themagnetized top wall 32 in the same manner as the top wall 32 waspreviously described to cooperate with the magnetic assembly 70. Thatis, the metal and magnetic structures are reversed but can be used in amanner corresponding to that for the structure shown in FIG. 1. Themagnitude of the attractive force, and thus the state of the bobbinassembly 12 and support 14, is similarly changed by removing one or moreof the metallic elements 72′, 74′, 76′, 78′, thereby producing a changein the magnitude of the attractive force between the bobbin assembly 12and support 14.

[0100] Still further, it is not required that the magnetic portion ormetallic portion, cooperating with the metallic or magnetic assemblies,be defined continuously on the wall 32. As shown in FIG. 22, an insert174 at the surface 62 of the wall 32′, corresponding to the wall 32, canbe either a metal set in a non-metal material or a metal with differentmagnetic properties than the metal in which it is inset. The cooperatingelement 176 on the flange 48′ is the complementary magnetic or metalliccomponent to produce the magnetically attractive rotational resistanceforce.

[0101] While the magnetic assembly 70, metallic assembly 172, andmetallic portions have been described as being on the case wall 32, andupper flange 48, all of the same structures, as heretofore described,could be incorporated to act in the same manner between the bottom wall26 of the bobbin basket 16 and the bottom flange 50 of the bobbinassembly 12.

[0102] As just one example, as shown in FIG. 24, the bobbin basket 16′has a magnetic/metallic element 178 embedded therein to cooperate with ametallic/magnetic element 180 that is bonded through an adhesive layer182 to the surface 64 of the flange 50. Additional metallic/magneticelements 180 may be provided and may be removably attached to functionas those described above.

[0103] In FIG. 25, a modification is shown wherein the metallic/magneticelement 180′, corresponding to that 180 in FIG. 3, is mounted within areceptacle 184 in the flange 50. As previously noted, each of theembodiments described above, including magnetic/metallic elementscooperating between the flange 48 and wall 32, can be utilized tocooperate between the flange 50 and wall 26.

[0104] Further, as previously mentioned, any construction of themagnetic and metallic assemblies 70, 172 could be provided on either ofthe support 14 or bobbin assembly 12, with the complementary metallicportion/magnetic portion provided on the other of the bobbin assembly 12and support 14. This is shown generically im FIGS. 26 and 27 and appliesto each embodiment disclosed herein.

[0105] As seen in FIGS. 28 and 29, it is also contemplated that the post24′ could be modified from that shown in FIG. 1 to incorporate amagnetic assembly at 186 consisting of magnetic elements 188, 190, 192,194, in the form of axially extending strips, which can be press fitinto complementary receptacles 196, 198, 200, 202, consecutively. Withthis construction, at least the bobbin assembly core 44 is madepartially or entirely from a metallic material that will cause anattractive force between the magnetic elements 188, 190, 192, 194 andthe bobbin assembly 12 to resist rotation of the bobbin assembly 12about its axis 28. One, and up to all, of the magnetic elements 188,190, 192, 194 can be removed to change the state of the support 14″ andbobbin assembly 12.

[0106] It is also contemplated that the cylindrical core 44 could bemagnetized, with the magnetic elements 188, 190, 192, 194 substitutedfor by similarly configured metallic elements defining a metallicassembly.

[0107] As shown in FIG. 30, the invention could be incorporated into anon-walled bobbin assembly as shown at 204. The concept, as disclosedwith respect to FIGS. 25 and 26, can be used to practice the inventionwith the non-walled bobbin assembly 204.

[0108] In FIGS. 31 and 32, a sewing system, according to the presentinvention, is shown at 210. The sewing system 210 corresponds to thatshown in U.S. Pat. No. 6,152,057, which is incorporated herein byreference. Briefly, the sewing system 210 consists of a support 212 fora bobbin assembly 214 having a thread supply 216 thereon. The thread 216from the. supply is wrapped spirally around an elongate member 218 onthe support 212. The number of wraps around the elongate member 218dictates the thread draw tension.

[0109] As shown in FIG. 32, the elongate member 218 consists of a core220 with a coating 222 thereon. It has been found that by using a lowfriction coating, such as a Teflon® coating, draw tension increase dueto the wrapping around the elongate member 218 can be kept relativelylow. As a consequence, the variation in the thread draw tension iseffected primarily through the magnetic/metallic assemblies 70, 172, andcooperating metallic/magnetic portions 206, 208, as shown in FIGS. 26and 27.

[0110] The inventive concept can be employed with virtually any type ofbobbin assembly and support. As just examples, the invention can beutilized with “pre-wound” bobbin assemblies, such as those made commonlyfrom cardboard and those identified as non-walled. Pre-wound bobbinassemblies are offered with a supply of thread thereon by amanufacturer.

[0111] The invention is useable likewise with bobbin assemblies that are“post-wound”. Typically, post-wound bobbin assemblies are made fromaluminum or other metal and are put in a winder to be loaded with asupply of thread at the particular facility at which sewing occurs.

[0112] The foregoing disclosure of specific embodiments is intended tobe illustrative of the broad concepts comprehended by the invention.

1. In combination: a) a bobbin assembly comprising: i) a core aroundwhich a supply of thread can be wrapped, the core having a rotationalaxis; and ii) a first flange having first and second oppositely facingsurfaces, with the first surface bounding a storage space for threadwrapped around the core; and b) a support for the bobbin assembly toallow the bobbin assembly to rotate around the rotational axis, saidsupport comprising: a third surface facing the second surface with thebobbin assembly operatively connected to the support, the bobbinassembly and support magnetically attracted to each other with a forceof a first magnitude with the bobbin assembly and support in a firststate, the force resisting rotation of the bobbin assembly around therotational axis, at least one of the bobbin assembly and supportreconfigurable to cause the bobbin assembly and support to be one of a)not magnetically attracted to each other and b) magnetically attractedto each other with a force of a second magnitude, that is different thanthe first magnitude, with the bobbin assembly and support in a secondstate.
 2. The combination according to claim 1 wherein there is amagnetic assembly on one of the bobbin assembly and support that isattracted to a metallic portion on the other of the bobbin assembly andsupport, and the bobbin assembly and support are changed from the firststate into the second state by separating a part of the magneticassembly from the one of the bobbin assembly and support.
 3. Thecombination according to claim 1 wherein there is a metallic assembly onone of the bobbin assembly and support that is attracted to a magneticportion on the other of the bobbin assembly and support, and the bobbinassembly and support are changed from the first state into the secondstate by separating a part of the metallic assembly from the one of thebobbin assembly and support.
 4. The combination according to claim 2wherein the magnetic assembly comprises a first magnetic element andwith the bobbin assembly and support in the second state, the firstmagnetic element is separated from the one of the bobbin assembly andsupport.
 5. The combination according to claim 2 wherein the magneticassembly comprises first and second magnetic elements and with thebobbin assembly and support in the second state, the first magneticelement is separated from the one of the bobbin assembly and support andthe second magnetic element remains on the one of the bobbin assemblyand support.
 6. The combination according to claim 4 wherein the firstmagnetic element is maintained on the one of the bobbin assembly andsupport by being magnetically attracted to the one of the bobbinassembly and support.
 7. The combination according to claim 4 whereinthe first magnetic element is maintained on the one of the bobbinassembly and support by a releasable adhesive.
 8. The combinationaccording to claim 2 wherein the magnetic assembly comprises a firstmagnetic element and the first magnetic element is separable from theone of the bobbin assembly and support by tearing a portion of themagnetic assembly to thereby change the bobbin assembly and support fromthe first state into the second state.
 9. The combination according toclaim 2 wherein the magnetic assembly is provided on the second flangeand the metallic portion is at the third surface.
 10. The combinationaccording to claim 2 wherein the support comprises a post which guidesrotation of the bobbin assembly around the rotational axis and themagnetic assembly is on the post.
 11. The combination according to claim2 wherein the magnetic assembly comprises a first magnetic element thatis releasably threadably attached to the one of the bobbin assembly andsupport.
 12. The combination according to claim 4 wherein the magneticassembly is maintained on the one of the bobbin assembly and support bycooperating releasably connecting parts on the magnetic assembly and theone of the bobbin assembly and support.
 13. The combination according toclaim 2 wherein the magnetic assembly comprises first and secondmagnetic elements and a carrier for the first and second magneticelements.
 14. The combination according to claim 13 wherein the carrierhas a weakened portion that can be torn to separate the first magneticelement from the one of the bobbin assembly and support to thereby placethe bobbin assembly and support in the second state.
 15. The combinationaccording to claim 13 wherein the carrier defines a first receptacle forthe first magnetic element and a second receptacle from the secondmagnetic element.
 16. The combination according to claim 13 wherein thecarrier is adhesively bonded to the one of the bobbin assembly andsupport.
 17. The combination according to claim 16 wherein the firstmagnetic element is bonded to the carrier.
 18. The combination accordingto claim 2 wherein the magnetic assembly is frictionally maintained onthe one of the bobbin assembly and support
 19. The combination accordingto claim 1 further comprising a rotary loop taken for drawing thread onthe bobbin assembly from the bobbin assembly.
 20. In combination: a) abobbin assembly comprising: a core around which a supply of thread canbe wrapped, the core having a rotational axis; b) a support for thebobbin assembly to allow the bobbin assembly to rotate around therotational axis, said support comprising: the bobbin assembly andsupport magnetically attracted to each other with a force of a firstmagnitude with the bobbin assembly and support in a first state, theforce resisting rotation of the bobbin assembly around the rotationalaxis, at least one of the bobbin assembly and support reconfigurable tocause the bobbin assembly and support to be one of a) not magneticallyattracted to each other and b) magnetically attracted to each other witha force of a second magnitude, that is different than the firstmagnitude, with the bobbin assembly and support in a second state.
 21. Amethod of controlling draw tension on thread pulled from a supply of thethread, the method comprising the steps of: providing a bobbin assemblycomprising a core around which a supply of thread can be wrapped, thecore having a rotational axis; providing a support for the bobbinassembly to allow the bobbin assembly to rotate around the rotationalaxis; producing a magnetic attractive force of a first magnitude betweenthe bobbin assembly and support with the bobbin assembly and support ina first state to resist rotation of the bobbin assembly around therotational axis; and selectively changing the support and bobbinassembly to a second state wherein one of a) the bobbin assembly andsupport are not attracted to each other and b) a magnetic attractiveforce of a second magnitude is produced between the bobbin assembly andsupport.
 22. The method according to claim 21 wherein the step ofproducing a magnetic attractive force comprises providing first andsecond magnetic elements on one of the bobbin assembly and support thatare attracted to a metallic portion on the other of the bobbin assemblyand support.
 23. The method according to claim 22 wherein the step ofselectively changing the support and bobbin assembly to the second statecomprises separating the first magnetic element from the one of thebobbin assembly and support and leaving the second magnetic element onthe one of the bobbin assembly and support.
 24. The method according toclaim 21 wherein the step of producing a magnetic attractive forcecomprises providing a first magnetic element on one of the bobbinassembly and support that is attracted to a metallic portion on theother of the bobbin assembly and support.
 25. The method according toclaim 24 wherein the step of selectively changing the bobbin assemblyand support to the second state comprises separating the first magneticelement from the one of the bobbin assembly and support.
 26. The methodaccording to claim 24 wherein the step of providing a first magneticelement comprises providing a first magnetic element on a carrier andattaching the carrier to the one of the bobbin assembly and support. 27.The method according to claim 26 wherein the step of selectivelychanging the bobbin assembly and support comprises tearing the carrierto allow separation of the first magnetic element from the one of thebobbin assembly and support.
 28. The method according to claim 24wherein the step of providing a first magnetic element comprisesreleasably attaching the first magnetic element to the one of the bobbinassembly and support.
 29. The method according to claim 21 wherein thestep of producing a magnetic attractive force comprises providing firstand second metallic elements on one of the bobbin assembly and supportthat are magnetically attractive to the other of the bobbin assembly andsupport.
 30. The method according to claim 28 wherein the step ofselectively changing the bobbin assembly and support to a second statecomprises separating the first metallic element from the one of thebobbin assembly and support.